CN113624372A - Pressure detection device based on optical fiber - Google Patents
Pressure detection device based on optical fiber Download PDFInfo
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- CN113624372A CN113624372A CN202110923042.2A CN202110923042A CN113624372A CN 113624372 A CN113624372 A CN 113624372A CN 202110923042 A CN202110923042 A CN 202110923042A CN 113624372 A CN113624372 A CN 113624372A
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 6
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
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Abstract
The invention relates to the field of pressure detection, in particular to a pressure detection device based on an optical fiber. The optical fiber comprises an optical fiber core, an optical fiber cladding, a stress part, an optical elastic material part and a substrate part. When the pressure measuring device is applied, the stress part compresses the optical elastic material part to change the refractive index of the optical elastic material part, namely, the change of the transmission path of laser in the fiber core of the optical fiber is changed, so that the intensity of emergent laser is changed, the reflectivity of the laser transmitted in the optical fiber is obtained by combining the incident light intensity, and the pressure to be measured is determined according to the reflectivity. Since the refractive index of the photoelastic material portion is strictly dependent on the pressure applied thereto, the present invention has an advantage of high pressure detection sensitivity. Meanwhile, the invention is based on the optical fiber, and the optical fiber has the characteristics of small volume, electromagnetic interference resistance, low price and long service life, so the pressure detection device provided by the invention has the advantages of small size, strong electromagnetic interference resistance, low cost and long service life.
Description
Technical Field
The invention relates to the field of pressure detection, in particular to a pressure detection device based on an optical fiber.
Background
The optical fiber is an abbreviation of optical fiber, and is a fiber made of glass or plastic, and can be used as a light conduction tool by utilizing the total reflection principle of light. The optical fiber consists of an optical fiber core, an optical fiber cladding and a coating layer, wherein the optical fiber core is surrounded by the optical fiber core cladding with the refractive index lower than that of the optical fiber core, laser is totally reflected on the interface of the optical fiber core and the optical fiber cladding, so that the laser is kept in the optical fiber core, and the outer surface of the optical fiber core is provided with the thin coating layer for protecting the optical fiber. Optical fibers are often used for long distance information transfer because the transmission loss of laser light in optical fibers is much lower than the transmission loss of electricity in electric wires. Optical fibers can be classified into single mode fibers and multimode fibers according to the number of modes of transmitted light. The optical fiber has the characteristics of small volume, electromagnetic interference resistance, low price and long service life.
The aspects of life and production all relate to pressure detection, and pressure detection is ubiquitous. At present, the principle of pressure detection is mainly to utilize the deformation of an elastic element to drive a pointer to swing to indicate pressure or to utilize the piezoresistive effect of a piezoresistive sensor to change the resistance value of a sensing part, so as to change physical quantities such as current and voltage in an external circuit to read the pressure. The former has large volume, the sensitivity of pressure detection and the service life of the device are completely dependent on the performance of the elastic element, the sensitivity is low and the service life is short; the latter is difficult to work normally in strong electromagnetic interference environment. These conventional pressure sensors cannot simultaneously meet the detection requirements of small size, high sensitivity, long life and electromagnetic interference resistance.
Disclosure of Invention
In order to solve the problems, the invention provides an optical fiber-based pressure detection device, which comprises an optical fiber core, an optical fiber cladding, a stress part, a photoelastic material part and a lining bottom part. The length of the optical fiber cladding is smaller than that of the optical fiber core, the optical fiber cladding is wrapped at one end of the optical fiber core, the photoelastic material portion is wrapped at the side periphery of the other end, which is exposed, of the optical fiber core, the optical fiber cladding is in tight contact with the photoelastic material portion, the sum of the lengths of the optical fiber cladding and the photoelastic material portion is equal to that of the optical fiber core, the substrate portion is arranged below the whole body of the optical fiber core and the photoelastic material portion, the length of the substrate portion is not smaller than that of the photoelastic material portion, the substrate portion is detachably and fixedly connected with the photoelastic material portion, the length of the stress portion is equal to that of the photoelastic material portion, the stress portion is arranged above the whole body of the optical fiber core and the photoelastic material portion, and the stress portion is fixedly connected with the photoelastic material portion.
Furthermore, the end face of the optical fiber core close to one end of the optical elastic material part is coated with a noble metal film.
Furthermore, the noble metal film material is gold or silver, and the film thickness is 50 nm-1000 nm.
Furthermore, the bottom of the liner is in a flat column shape, the bottom surface of the flat column shape, namely the upper surface or the lower surface of the liner is in a triangle shape, a gear shape or a rectangle shape, and the liner is made of opaque rigid materials.
Furthermore, the upper surface of the stress part is a plane with an area larger than that of the lower surface of the substrate part, the lower surface of the stress part is a circular arc surface matched with the photoelastic material part, and the stress part is made of lightproof rigid material.
Furthermore, a groove is arranged on the lower surface of the stress part, penetrates through the photoelastic material part, and can be in a wedge shape or a rectangular shape.
Furthermore, the outer surface of the photoelastic material part is also provided with a noble metal film, the noble metal film is made of gold or silver, and the thickness of the noble metal film is 500 nm-1500 nm.
Furthermore, the end part of the optical fiber core close to the photoelastic material part is in a convex shape, and the convex shape is a pointed cone, a hemisphere or a spherical segment.
Further, the interior of the photoelastic material portion is provided with a block of material.
Furthermore, the material of the photoelastic material part is quartz glass, epoxy resin or gelatin.
The invention has the beneficial effects that: the invention provides a pressure detection device based on an optical fiber. The optical fiber laser comprises a laser, an optical detector, an optical fiber core, an optical fiber cladding, a stress part, an optical elastic material part and a substrate part. During application, under the action of pressure to be measured, the stress part compresses the photoelastic material part, the refractive index of the photoelastic material part is changed, namely the reflection characteristic of the interface between the optical fiber core and the photoelastic material part is changed, and the propagation path of laser in the optical fiber core is changed, so that the intensity of emergent laser detected by the optical detector is changed, and the reflectivity of the laser propagating in the optical fiber can be obtained by combining the incident intensity of the laser, namely the pressure to be measured can be determined through the reflectivity of the laser. Since the refractive index of the photoelastic material portion is strictly dependent on the pressure applied thereto, the present invention has an advantage of high pressure detection sensitivity. Meanwhile, the invention is based on the optical fiber, and the optical fiber has the characteristics of small volume, electromagnetic interference resistance, low price and long service life, so the pressure detection device provided by the invention has the advantages of small size, strong electromagnetic interference resistance, low cost and long service life.
The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
FIG. 1 is a schematic front cross-sectional view of an optical fiber-based pressure sensing device.
FIG. 2 is a schematic side cross-sectional view of a pressure sensing portion of an optical fiber-based pressure sensing device.
FIG. 3 is a schematic side sectional view of a pressure sensing portion of an optical fiber-based pressure sensing device.
FIG. 4 is a schematic side sectional view of a pressure sensing portion of an optical fiber-based pressure sensing device.
FIG. 5 is a schematic side sectional view of a pressure sensing portion of an optical fiber-based pressure sensing device.
FIG. 6 is a schematic side sectional view of a pressure sensing portion of an optical fiber-based pressure sensing device.
Fig. 7 is a schematic front sectional view of the pressure detecting device shown in fig. 6.
FIG. 8 is a schematic front cross-sectional view of an optical fiber-based pressure sensing device.
FIG. 9 is a schematic front cross-sectional view of yet another fiber-based pressure sensing device.
FIG. 10 is a schematic front cross-sectional view of yet another fiber-based pressure sensing device.
In the figure: 1. a laser; 2. a light detector; 3. a fiber core; 4. a fiber cladding; 5. a force receiving portion; 6. a photoelastic material portion; 7. a first noble metal thin film; 8. a substrate portion; 9. a cushioning material portion; 10. a second noble metal thin film; 11. a block of material.
Detailed Description
To further explain the technical means and effects of the present invention adopted to achieve the intended purpose, the following detailed description of the embodiments, structural features and effects of the present invention will be made with reference to the accompanying drawings and examples.
Example 1
The invention provides a pressure detection device based on an optical fiber, which comprises an optical fiber core 3, an optical fiber cladding 4, a stress part 5, a photoelastic material part 6 and a lining bottom part 8, as shown in figure 1. The length of the optical fiber cladding 4 is less than that of the optical fiber core 3, a section of the optical fiber core 3 is exposed, the propagation path of laser in the optical fiber core 3 strictly depends on the interface formed by the optical fiber core 3 and adjacent materials, and the exposed optical fiber core 3 is convenient for pressure detection; the optical fiber cladding 4 is wrapped at one end of the optical fiber core 3, so that the end part of the optical fiber core 3 is positioned at a pressure detection part, the end part of the optical fiber core 3 is convenient to change, and the sensitivity of pressure detection is improved; the optical elastic material part 6 is wrapped on the side periphery of the bare optical fiber core 3, so that an interface is formed between the bare optical fiber core 3 and the optical elastic material part 6, the shape of the interface is a cylindrical curved surface, and laser in the optical fiber core 3 is totally reflected on the cylindrical curved surface; the optical fiber cladding 4 is in close contact with the photoelastic material part 6, no narrow gap exists, the sum of the lengths of the optical fiber cladding 4 and the photoelastic material part 6 is equal to the length of the optical fiber core 3, and therefore the side periphery of the optical fiber core 3 is wrapped by the optical fiber cladding 4 and the photoelastic material part 6, and laser is transmitted in the optical fiber core 3; the substrate part 8 is arranged right below the whole body of the optical fiber core 3 and the photoelastic material part 6, and the length of the substrate part 8 is not less than that of the photoelastic material part 6, so that the substrate part 8 can effectively support the photoelastic material part 6, the photoelastic material part 6 is protected, and meanwhile, the substrate layer 8 can be better fixed on a to-be-detected stressed object; the substrate part 8 and the photoelastic material part 6 are detachably and fixedly connected, so that the substrate part 8 can be fixed at different positions on the outer side surface of the photoelastic material part 6, and pressure detection is performed under the condition that the force applying direction of a force applying object is not perpendicular to the surface of a force object to be detected; the stress part 5 is arranged right above the whole of the optical fiber core 3 and the photoelastic material part 6, the length of the stress part 5 is equal to that of the photoelastic material part 6, and the stress part 5 is fixedly connected with the photoelastic material part 6, so that the stability of the stress part 5 in stress is improved; the stress part 5 and the substrate part 8 are made of opaque rigid materials, the stress part 5 and the substrate part 8 can be made of the same or different materials, preferably, the stress part 5 and the substrate part 8 are made of the same materials, so that the stress part 5 and the substrate part 8 have the same elastic modulus, the deformation amount under the action of the stress object and the force applying object is basically equivalent to that under the action of the reaction force, and detection errors are not easily caused. The material of the photoelastic material portion 6 is a photoelastic material, and specifically, the material of the photoelastic material portion 6 is quartz glass, epoxy resin, or gelatin.
When manufacturing, the optical fiber used in the invention can be quartz optical fiber or plastic optical fiber, preferably, quartz optical fiber is used; the optical fiber used in the present invention may be either a single mode optical fiber or a multimode optical fiber. Firstly, removing a section of coating layer at one end of an optical fiber to expose the cladding of the optical fiber, and then removing a section of cladding around the end part of the optical fiber core 3 by using an optical fiber polishing and grinding machine to expose a section of the optical fiber core 3; finally, the periphery of the bare fiber core 3 is coated with a photoelastic material, and the stress part 5 and the substrate part 8 are fixed to the upper and lower sides of the photoelastic material, respectively.
When the device is applied, the substrate part 8 is fixed at a proper position on the outer side surface of the photoelastic material part 6 according to the relation between the pressure direction to be measured and the surface of a stressed object, and the substrate part 8 is fixed on the surface of the stressed object. When the pressure to be measured acts on the stress part 5, the stress part 5 compresses the photoelastic material part 6, the refractive index of the photoelastic material part 6 is changed, and the reflection characteristic at the interface between the optical fiber core 3 and the photoelastic material part 6 is changed; laser emitted by the laser 1 is incident from the end face of the optical fiber core 3 close to one end of the optical fiber cladding 4, is totally reflected on the interface of the optical fiber core 3 and the optical elastic material part 6, because the pressure to be measured changes the reflection characteristic of the interface between the optical fiber core 3 and the optical elastic material part 6, namely under different detection pressures, the propagation path and energy loss of the laser in the optical fiber core 3 coated with the optical elastic material are different, the laser is reflected on the end face of the optical fiber core 3 close to one end of the optical elastic material part 6 and enters the optical fiber core 3 coated with the optical elastic material again for propagation, finally is emitted from the end face of the optical fiber core 3 close to one end of the optical fiber cladding 4, the intensity of the reflected light is detected by the optical detector 2, and the incident light intensity of the laser 1 is combined, the reflectivity under different detection pressures is obtained, and the reflection spectrum can be obtained by changing the incident wavelength or the pressure to be detected. Since the refractive index of the photoelastic material portion is strictly dependent on the pressure applied thereto, the present invention has an advantage of high pressure detection sensitivity. Meanwhile, the invention is based on the optical fiber, and the optical fiber has the characteristics of small volume, electromagnetic interference resistance, low price and long service life, so the pressure detection device provided by the invention has the advantages of small size, strong electromagnetic interference resistance, low cost and long service life.
Example 2
Based on embodiment 1, as shown in fig. 2, the first noble metal thin film 7 is coated on the end surface of the optical fiber core 3 near one end of the photoelastic material portion 6, the material of the first noble metal thin film 7 is a noble metal material, preferably, the material of the first noble metal thin film 7 is gold or silver, the thickness of the first noble metal thin film 7 is 50nm to 1000nm, the noble metal material has a good reflection performance to light, so that the end surface of the optical fiber core 3 near one end of the photoelastic material portion 6 reflects more laser light, and the reflected laser light enters the optical fiber core 3 again, which enhances the effect of changing the laser propagation path, changes the intensity of the emitted laser light more, and improves the sensitivity of pressure detection.
Example 3
In addition to embodiment 2, the shape of the photoelastic material portion 6 may be a hollow sphere, a rectangular parallelepiped, a cylinder, or the like having a penetrating cylindrical shape in the middle, and the size of the middle hollow cylinder matches the optical fiber core 3, and preferably, the shape of the photoelastic material portion 6 is a hollow cylinder having a penetrating cylindrical shape in the middle. The bottom surface of the hollow cylinder is a concentric ring, the inner diameter of the concentric ring is the diameter of the end surface of the optical fiber core 3, and the outer diameter is larger than or equal to the outer diameter of the optical fiber cladding 4. The concentric circular rings are symmetrical, so that the substrate part 8 can be fixed on the outer side surface of the photoelastic material part 6 at a position forming any angle with the direction of the pressure to be measured, and the pressure to be measured when the pressure to be measured is not perpendicular to the surface of a stressed object can be measured. Meanwhile, because the concentric rings are symmetrical, when the force is applied along different directions, the change of the refractive index of the photoelastic material part 6 is completely the same, so that the small error caused by measuring the pressure to be measured at different angles can be eliminated, and the accuracy of the detection device is improved.
Example 4
On the basis of embodiment 3, as shown in fig. 3, the liner bottom portion 8 is a flat column, and the bottom surface of the flat column may be triangular, gear-shaped, or rectangular; the force receiving portion 5 may or may not be a flat column, and the bottom surface of the flat column may be triangular, gear-shaped, or rectangular. The shape of the liner bottom part 8 and the shape of the flat columnar bottom surface of the force receiving part 5 can be the same or different. The bottom surface of the flat columnar shape of the liner bottom part 8 or the stress part 5 is triangular, the triangle is an isosceles triangle, and the contact surface of the liner bottom part 8 and the photoelastic material part 6 is a symmetry axis of the isosceles triangle, so that the liner bottom part 8 or the stress part 5 can be fixed at a special position with a narrow inside and a wide outside; the flat columnar bottom surface of the liner bottom part 8 or the stress part 5 is in a gear shape, and a plurality of protruding parts are arranged on the periphery of the gear shape, so that the liner bottom part 8 can be conveniently fixed on a force application object to be tested or the stress part 5 can be conveniently fixed on the force application object; the bottom surface of the flat column of the liner bottom part 8 or the stress part 5 is rectangular, the rectangle has four right angles and two long edges, the fixing mode is flexible, and the liner bottom part 8 is conveniently fixed on a force application object to be tested or the stress part 5 is conveniently fixed on the force application object. By replacing the substrate part 8 or the force receiving part 5 with different shapes, the applicability of the detection device is improved.
Example 5
On the basis of embodiment 4, as shown in fig. 4, the contact surface of the substrate portion 8 and the photoelastic material portion 6 is a curved surface, and the upper surface of the substrate portion 8 has a circular arc-shaped groove matching with the photoelastic material portion 6, so that the photoelastic material portion 6 can be more easily fixed to the substrate portion 8; the upper surface of stress portion 5 is the plane that an area is greater than bottom of the lining portion 8 lower surface, and the lower surface is the arc surface that coincide with photoelastic material portion 6, can fix photoelastic material portion 6 on stress portion 5 more easily like this, and simultaneously, great upper surface has increased the area of contact of stress portion 5 with the application of force thing to stress portion 5 transmits stronger effort to photoelastic material portion 6, has improved detection device's response intensity.
Example 6
On the basis of embodiment 5, as shown in fig. 5, the lower surface of the stress portion 5 is provided with a groove, the groove penetrates through the photoelastic material portion 6, the shape of the groove can be any shape such as wedge, rectangle, etc., the number of the grooves can be odd or even, the arc length of the groove does not exceed one half of the arc length of the contact arc surface between the stress portion 5 and the photoelastic material portion 6, which is beneficial to ensuring the stability of the device, the existence of the groove reduces the contact area between the stress portion 5 and the photoelastic material portion 6, increases the pressure of the stress portion 5 to the photoelastic material portion 6, increases the number of stress points of the photoelastic material portion 6, increases the refractive index change of the local photoelastic material portion 6, changes the refractive index of the photoelastic material portion 6 unevenly, and the reflection characteristics on the interfaces between the optical fiber core 3 and each photoelastic material portion 6 are not completely the same, this increases the complexity of the laser propagating on the interface between the fiber core 3 and the photoelastic material portion 6, greatly changes the intensity of the emitted laser, and improves the sensitivity of the detection device.
Example 7
In example 6, as shown in fig. 6, a cushioning material portion 9 was fixedly provided in the groove of the force receiving portion 5, the cushioning material portion 9 was an elastic material, the cushioning material portion 9 was an elongated strip having a length equal to the length of the photoelastic material portion 6, and the cross-sectional shape substantially coincided with the shape of the groove, except that the cushioning material portion 9 did not completely fill the groove, and an air gap having a height of about 2 to 3 μm was left in the innermost portion of the groove. Like this when the external force that receives of atress portion 5 was too big, atress portion 5 takes place deformation downwards, and buffer material portion 9 can contact with atress portion 5 to take place deformation, offset the influence that too big external force brought, protected photoelastic material portion 6, this security that has improved detection device.
Example 8
In example 7, as shown in fig. 7 and 8, a second noble metal thin film 10 is further provided on the outer surface of the photoelastic material portion 6, the material of the second noble metal thin film 10 is a noble metal material, preferably, the material of the second noble metal thin film 10 is gold or silver, and the thickness of the second noble metal thin film 10 is 500nm to 1500 nm. The noble metal material has good reflection performance to light, so that light entering the photoelastic material part 6 enters the photoelastic material part 6 again after being reflected, passes through the interface of the photoelastic material part 6 and the optical fiber core 3, and enters the optical fiber core 3, so that the optical detector 2 can detect the intensity of light related to more detection pressure, and the sensitivity of the detection device is enhanced.
Example 9
In example 8, the end of the optical fiber core 3 near the photoelastic material portion 6 was convex, and specifically, the end of the optical fiber core 3 near the photoelastic material portion 6 was pointed cone, hemisphere, or spherical segment. The end of the optical fiber core 3 close to the photoelastic material portion 6 greatly affects the reflected light, and by changing the shape of the end, when the reflected laser light passing through the first noble metal thin film 7 on the outer side of the end surface is reflected on the interface of the optical fiber core 3 and the photoelastic material portion 6, the propagation path is changed more, so that the light intensity of the emitted laser light is greatly changed, and the sensitivity of the detection device is improved. The end part of the optical fiber core 3 close to the optical elastic material part 6 is in a pointed cone shape, the first noble metal film 7 on the outer side of the pointed cone surface can reflect laser entering the pointed cone, so that the direction of the reflected laser is dispersed, and in addition, the pointed cone-shaped end part is easy to prepare; the shape of the end part of the optical fiber core 3 close to the photoelastic material part 6 is a hemisphere, the first noble metal film 7 on the outer side of the hemispherical surface can reflect laser entering the hemisphere, the focal point of the hemisphere is on the center of the hemisphere, all reflected light in the hemisphere can pass through the center of the hemisphere, which is equivalent to that a point light source is arranged at the center of the hemisphere, the dispersibility of the reflected laser is increased, and the direction of the reflected laser is more dispersed; the shape of the end part of the optical fiber core 3 close to the photoelastic material part 6 is a segment, the first noble metal film 7 on the outer side of the segment can reflect laser entering the segment, the curvature radius of the segment is larger than that of a corresponding hemisphere, the focus of the segment is positioned on the inner axis of the optical fiber core 3, namely a point light source is placed on the inner axis of the optical fiber core 3, so that the directions of reflected light on the interface of the optical fiber core 3 and the photoelastic material part 6 are more diversified, and the dispersibility of the reflected laser is further increased. This effectively increases the sensitivity of the detection apparatus of the present invention.
Example 10
On the basis of embodiment 9, as shown in fig. 9, a material block 11 is disposed in the photoelastic material portion 6, the material block 11 may be any shape such as a sphere, a cuboid, a tetrahedron, and the like, the shape, the size, and the interval of the material block 11 may be the same or different, the shape, the size, and the interval of the material block 11 are the same, regardless of the relationship between the direction of the pressure to be measured and the surface of the load, the refractive index change of the photoelastic material portion 6 caused by the material block 11 is consistent, and the comparability and the repeatability of pressure detection are high; when the shapes, sizes and intervals of the material blocks 11 are different, under the compression of the stress part 5, the stress on the inner surface of the photoelastic material part 6 is more diversified in magnitude and direction, so that the overall refractive index of the photoelastic material part 6 is more changed, the path of laser propagating in the optical fiber core 3 is more changed, the light intensity of the emitted laser is more changed, and the pressure detection sensitivity is improved. The material of the material blocks 11 can be silicon dioxide, noble metal and elastic material, and the material of the material blocks 11 can be the same or different. When the material block 11 is made of noble metal, under the action of an optical field, local plasmon polarization occurs on the surface of the noble metal, and the optical field energy near the noble metal is concentrated on the surface of the noble metal, so that the refractive index of the photoelastic material near the noble metal is changed, the path of laser propagation in the optical fiber core 3 is changed, the light intensity of the emergent laser is changed more, and the pressure detection sensitivity is improved; in addition, the two noble metals which are closer to each other are mutually coupled, so that the refractive index of the surrounding photoelastic material is changed more, and the detection sensitivity of the invention is further improved. Under the action of an external force to be detected, the stress part 5 compresses the photoelastic material part 6, the photoelastic material part 6 has a photoelastic effect, the refractive index of the photoelastic material part can change when the photoelastic material part is stressed, the material block 11 embedded in the photoelastic material part 6 enables some surfaces inside the photoelastic material part 6 to be stressed, the photoelastic effect of the photoelastic material part 6 is enhanced, the refractive index of the photoelastic material part 6 is changed more, the path change of laser reflected on the interface of the optical fiber core 3 and the photoelastic material part 6 is large, the light intensity change of the emergent laser is large, and the sensitivity of the monitoring device is improved.
Example 11
Unlike embodiment 10, as shown in fig. 10, the block 11 is provided only at the interface with the optical fiber core 3 within the photoelastic material portion 6. The material block 11 can be any shape such as a sphere, a cuboid, a tetrahedron, etc., preferably, the material block 11 is a sphere, one section of the sphere is the interface between the optical fiber core 3 and the photoelastic material portion 6, and light is transmitted along a straight line, so that laser in the optical fiber core 3 is easily introduced into the material block 11. The material of the material block 11 can be noble metal or silicon dioxide, the material of the material block 11 is noble metal, local plasmon polarization occurs on the surface of the noble metal under the action of an optical field, the optical field energy near the noble metal is concentrated on the surface of the noble metal, and the refractive index of the photoelastic material near the noble metal is changed, so that the path of laser propagating in the optical fiber core 3 is changed, the intensity of the emergent laser is changed more, and the pressure detection sensitivity is improved; the material block 11 is made of silicon dioxide, after laser enters the silicon dioxide, the laser passes through the interface between the optical fiber core 3 and the photoelastic material part 6 after being reflected for multiple times in the silicon dioxide and enters the optical fiber core 3, and the silicon dioxide changes the propagation path of the laser, so that the light intensity of the emergent laser is changed, and the detection sensitivity of the device is improved. The sizes of the material blocks 11 can be the same or different, the intervals of the material blocks 11 can be the same or different, preferably, the intervals of the material blocks are different, so that the intervals of the material blocks 11 are long or short, the coupling effect strength among the material blocks 11 is related to the intervals, the refractive indexes of all parts on the interface of the optical fiber core 3 and the photoelastic material part 6 are different, the directions of reflected light of the interface are different, the propagation path of laser in the optical fiber core 3 is more complex, the light intensity of the emitted laser is greatly changed, and the sensitivity of the pressure detection device is improved.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions may be made without departing from the spirit of the invention, which should be construed as belonging to the scope of the invention.
Claims (10)
1. A pressure detection device based on an optical fiber is characterized by comprising an optical fiber core, an optical fiber cladding, a stress part, a photoelastic material part and a substrate part, wherein the length of the optical fiber cladding is smaller than that of the optical fiber core, the optical fiber cladding is wrapped at one end of the optical fiber core, the photoelastic material part is wrapped at the side periphery of the other end, which is exposed, of the optical fiber core, the optical fiber cladding is in close contact with the photoelastic material part, the sum of the lengths of the optical fiber cladding and the photoelastic material part is equal to that of the optical fiber core, the substrate part is arranged below the optical fiber core and the photoelastic material part integrally, the length of the substrate part is not smaller than that of the photoelastic material part, the substrate part is detachably and fixedly connected with the photoelastic material part, and the length of the stress part is equal to that of the photoelastic material part, the stress part is arranged above the optical fiber core and the optical elastic material part, and the stress part is fixedly connected with the optical elastic material part.
2. An optical fiber-based pressure sensing device as defined in claim 1, wherein: the end face of the optical fiber core close to one end of the optical elastic material part is coated with a noble metal film.
3. An optical fiber-based pressure sensing device as defined in claim 2, wherein: the bottom of the liner is in a flat column shape, the bottom surface of the flat column shape, namely the upper surface or the lower surface of the bottom of the liner, is in a triangular shape, a gear shape or a rectangular shape, and the bottom of the liner is made of opaque rigid materials.
4. An optical fiber-based pressure sensing device as defined in claim 3 wherein: the upper surface of the stress part is a plane with an area larger than that of the lower surface of the substrate part, the lower surface of the stress part is an arc surface matched with the photoelastic material part, and the stress part is made of opaque rigid material.
5. An optical fiber-based pressure sensing device as defined in claim 4 wherein: the lower surface of the stress part is provided with a groove, the groove penetrates through the photoelastic material part, and the shape of the groove can be wedge-shaped or rectangular.
6. An optical fiber-based pressure sensing device as defined in claim 5, wherein: the outer surface of the photoelastic material part is also provided with a noble metal film, the noble metal film is made of gold or silver, and the thickness of the noble metal film is 500-1500 nm.
7. An optical fiber-based pressure sensing device as defined in claim 6, wherein: the end part of the optical fiber core close to the photoelastic material part is in a convex shape, and the convex shape is a pointed cone, a hemisphere or a spherical segment.
8. The optical fiber-based pressure sensing device of claim 7, wherein: the inside of the photoelastic material part is provided with a material block.
9. An optical fiber-based pressure sensing device as defined in claim 1, wherein: the material of the photoelastic material part is quartz glass, epoxy resin and gelatin.
10. An optical fiber-based pressure sensing device as defined in claim 2, wherein: the noble metal film material is gold or silver, and the thickness of the film is 50 nm-1000 nm.
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| CN113624372B (en) | 2023-04-21 |
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